title: Peptic peptide of thiolsubtilisin. Analytical evidence for the chemical transformation of the essential serine-221 to cysteine-221.
abstract: Direct evidence is offered to show that the active site Ser-221 of subtilisin is transformed into a cysteine residue in the chemical procedure previously elaborated for the preparation of thiolsubtilisin. Thiolsubtilisin was digested with pepsin and the hydrolyzate was applied to an agarose-mercurial column. After elution with 2-mercaptoethanol a single tetrapeptide was obtained. Dansyl-Edman degradation showed that the SH-peptide conformed to the amino acid sequence around the active site Ser-221 of subtilisin. A simple, single-step procedure for isolation of SH-peptides is also described.
mesh_terms: D000595:Amino Acid Sequence; D001665:Binding Sites; D055598:Chemical Phenomena; D002621:Chemistry; D003545:Cysteine; D009842:Oligopeptides / Q000302:isolation & purification; D010434:Pepsin A; D010446:Peptide Fragments; D012694:Serine; D013381:Subtilisins; D013438:Sulfhydryl Compounds / Q000302:isolation & purification
chemical_list: D009842:Oligopeptides; D010446:Peptide Fragments; D013438:Sulfhydryl Compounds; D012694:Serine; D013381:Subtilisins; C022743:thiolsubtilisins; D010434:Pepsin A; D003545:Cysteine